The Tragedy of the Commons

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The Tragedy of the Commons

• Craig Callender
• Philosophy, UCSD

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Hardin and the Tragedy

• Garrett Hardin 1915-2003
• Ecologist, microbiologist, Professor, UCSB
• TOC 1968 Living on a Lifeboat 1974
• TOC reprinted in over 100 anthologies
  tremendously influential in ecology, population
  studies, econ, pol sci

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The Tragedy Background

• Benthams goal the greatest good for the
  greatest number is impossible.
• Maximizing population v. maximizing goods
• Hardin wants to argue against our present policy
  of laissez-faire in population

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Full disclosure
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• Look at all the environmental damage we human
  beings do. Is there some kind of general hidden
  dynamics/ mechanism at work responsible for
  some/all of this?
• If we find the deepest cause, maybe we can find
  general type of solution.

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Tragedy of the Commons

• Assume a common-property resource (exclusion is
  difficult and joint use involves
  subtractability), I.e., no property rights.
• E.g.pasture open to all
• Assume each herdsman tries to keep as many sheep
  as possible on the commons. They each try to
  maximize gain.

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Tragedy, continued

• What is the utility to me of adding one more
  animal to my herd?
• The positive component is a fn of the increment
  of one animal. Since the herdsman receives all
  the proceeds from the sale of each additional
  animal, the positive utility is nearly 1
• The negative component is a fn of the additional
  overgrazing created by one more animal. This is
  shared by all herdsmen, so neg utility is only a
  fraction of -1.

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Add those sheep!

• The rational herdsman concludes that he or she
  should add another sheep.
• And another
• And another
• And so does each herdsman
• Ruin is the destination toward which all men
  rush, each pursuing his own best interest

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Possible Tragic Commons?

• National Parks
• Forests
• Marine life
• Air
• Pollution
• Ecosystems
• Etc.

Hardin privatize or manage population problem
aggravates everything else, calling for a
redefinition of property rights
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Prisoners Dilemma
cooperate
defect
cooperate
defect
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Fishing Tragedy
Restrict catch
Dont restrict catch
restrict
Dont restrict
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Population

• Conscience, education, etc., wont work, he says,
  because it is in ones self-interests to breed.
  Hence coercion needed.
• We have abandoned the commons for some food
  production, waste disposalnow, Hardin claims, it
  is time to abandon freedom to breed.
• Life boat ethics Hardin is against World Food
  Bank

• Overpopulation is a commons tragedy too, Hardin
  claims.
• Parents gain from children, but dont bear full
  costs due to welfare state.
• Against the right to breed.

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Questions

• Is there a right to breed? What are the ethical
  ramifications of denying it?
• Is overpopulation really a tragedy problem? Is
  Hardin right?
• How many other scenarios mentioned are really
  tragedy problems?

• (For answers to the second question, I draw in
  part on Gardiners essay _at_
• http//muse.jhu.edu/journals/philosophy_and_public
  _affairs/toc/pap30.4.html)

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Ethics of Breeding

• The big question even if there is no right to
  breed, are the consequences of enforcing a
  coercive policy themselves worse than the
  consequences of not doing so?

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Is overpopulation a TOC?

• PD1 It is collectively rational to cooperate
  each agent prefers the outcome produced by
  everyone cooperating over the outcome produced by
  no one cooperating.
• PD2 It is individually rational not to
  cooperate when each individual has the power to
  decide whether or not she will cooperate, each
  person (rationally) prefers not to cooperate,
  whatever the others do.

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Is overpopulation a TOC?

• Population-PD1 It is collectively rational to
  have smaller families Each agent prefers the
  outcome produced by everyone having smaller
  families over the outcome produced by everyone
  having large families.
• Population-PD2 It is individually rational to
  have a large family when each individual has the
  power to decide whether or not she will have a
  large or small family, each person (rationally)
  prefers to have a large family, no matter what
  everyone else does.

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Why does game have this structure? Hardin thinks
having more children is always beneficial. Why?
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(No Transcript)
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• If each human family were dependent only on its
  own resources if the children of improvident
  parents starved to death if, thus, overbreeding
  brought its own "punishment" to the germ
  line--then there would be no public interest in
  controlling the breeding of families. But our
  society is deeply committed to the welfare state,
  and hence is confronted with another aspect of
  the tragedy of the commons. In a welfare state,
  how shall we deal with the family, the religion,
  the race, or the class (or indeed any
  distinguishable and cohesive group) that adopts
  overbreeding as a policy to secure its own
  aggrandizement? To couple the concept of freedom
  to breed with the belief that everyone born has
  an equal right to the commons is to lock the
  world into a tragic course of action.

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• Hardins argument here sometimes seem to turn
  biologicalone wants to perpetuate the germ
  line. But thats not what is going on.
• PD2 seems false.
• Moreover, empirically one sees that a combination
  of (a) providing equal educational and
  occupational rights for women, (b) criminalizing
  child labor, and (c) reproductive freedom
  falsifies PD2.

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How General are Tragedies?

• How realistic is any game-theoretic model? How
  does one confirm or deny game theory? Big
  philosophical questions heresee
  http//plato.stanford.edu/entries/game-theory/
• Single v multi period game players communicate
  in finite horizon game, incentive to defect only
  on next to last play
• Hirshleifer and Rimmusen 1989 just a bit of
  morality makes cooperation dominant strategy
• Behavioral economics

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How Many Commons Are There?

• Exclusion fishing for migratory species v for
  oysters
• Subtractability for some populations, culling
  might be good
• Property rights come in many forms private,
  communal, state, de facto
• Hardin-like models assume open access, free
  entry, free exit, lack of property rights
• Carmel Finlays talk

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Cost Distribution Issue

• Those who cause environmental damage may not be
  among those incurring the costs of such damage.

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Intergenerational Problem

• 1st preference I pollute, you don't.
• 2nd preference No one pollutes.
• 3rd preference Everyone pollutes.
• 4th preference You pollute, I don't.

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Global Warming a TOC?

• Intergenerational-1 It is collectively rational
  for most generations to cooperate (almost) every
  generation prefers the outcome produced by
  everyone restricting pollution over the outcome
  produced by everyone overpolluting.
• Intergenerational-2 It is individually rational
  for all generations not to cooperate when each
  generation has the power to decide whether or not
  it will overpollute, each generation (rationally)
  prefers to overpollute, whatever the others do.

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Conclusion Big questions

• What is manageable? And how? Taxes to simulate
  market for the air?
• What is (morally) privatizable?
• Is breeding a right? If not, how would this be
  enforced?
• How does one confirm or falsify game theoretic
  models?
• How common are TOCs?